Drawing instrument.



A. S HARCOS.

DRAWING INSTRUMENT.

APPLICATION FILED MAR. 26, i918.

1,299, 179. Patented Apr. 1,1919.

INVEN TOR. A SJVAR [05 A TTORNE Y.

scale.

ALADAB, s. HARCOS, or sAN FRANCISCO, CALIFORNIA.

DRAWING INSTRUMENT.

Specification of Letters Patent.

Patented Apr. 1, 1919.

Application filed March 26, 1918. Serial No. 224,701.

To all whom it may concern Be it known that LALADAR'S. HARcos, a citizen of the United States, residing at San Francisco, in the county of San Francisco and State of California, have invented new and useful Improvements in Drawing Instruments, of which the following is a speci fication. I

Draftsmen who draw to scale use numerous scale rulers for ascertaining the lengths oflines representing, generally in a reduced proportion, the lengths of other lines on a different scale. These scales are known as, among others, a 3-inch scale, a 1% -inch scale, a 1-inch scale, a -}-inch scale, a g-inch scale, a 3-inch scale, a i inch scale, and a inch Other scales are sometimes found, but the above are the ones most commonly used. Heretofore the most satisfactory embodiment of such scales was in the form of thin, fiat strips of wood, or other suitable material, properly graduated for the particular scale required. Or one such ruler may carry" two different scales, one on eachedge. Another embodiment of these scales is that ofthe polyhedral ruler, having two scales marked on each edge. But all such scales are inconvenient and their use involves consumption of time in turning from one scale to the other. Moreover, such scales require the marking of 'the paper as by pricking the same, to be done in a separate operation.

One object of the invention is to provide a single instrument which can be used in a single operation to mark, by pricking the same on the paper, an "interval corresponding to any one desired of a large 'number of scales.

A further object is to provide an instrw ment which can be used with great convenience as an ordinary divider.

A further object is to provide an instrument which, when usedas a proportional divider, will be much more convenient than proportional dividers at present in use.

A further object is toprovide an instru ment which can be used veryconveniently as a protractor.

"In the accompanying drawing, Figure 1 is a broken front view of my improved instrument; Fig. 2 is. a longitudinahcentral detached.

Referring to the drawing, v1 indicates stationary clrcular case -havin'g integrally connected therewith one end of a leg 2. In

diametrically opposite portions of the circumference of the case 1 are slots 3 and 4.

I Theslot 3 is always closed by the outer edge of a curved rack 6 which oscillates in close Contact with the circumferential portion of the case '1. Through said rack, and also I through the slot 3, extends a movable leg 7. Sand legs 2 and 7 are formed at their free ends with recesses 8 to receive pins 9 adjustably secured by set screws 11. The inner end of the leg 7 isrotatably mounted .upon a shaft 12, screwed into a central boss 13 extendinginwardly from the inner surface of the case 1. When said leg 7- is oscillated about said shaft 12 it' carries with it the curved rack 6, thereby rotating an idler gear wheel 14, meshing with said rack and mounted upon a hub 16 secured by a screw 17 to a boss 18 extending inwardly from theinner surface'of said case 1. The portion of the leg 7 which is contained withinIthe casing 1 isreces'sed, as shown at 19, to enable it to pass on'each side of said hub 16. The rotation ofth'e idler gear wheel 14 rotates a pinion 21 which rotatably surrounds a hub 22 secured around the shaft 12. Said pinion isformed integral with a dial 23, and therefore the dial rotates with the leg 7, but at 'a greater angular speed. The parts are of such proportions that, whenthe leg 7 is moved through the full length of the slot 3, and the dial 23 makes nearly a complete revolution, so that the ends 24 of concentric circular scale lines 26 coincide with a radially extending hair line 27 marked on a sta tionary crystal 28 secured in the case 1, with which hair line the beginnings of the circular scale l1nes 26 coincide or register when the legs 2 and 7 are close together','as-shown in Fig. 1. There may be any number of such circular scale lines but only four are here shown. However, by using graduations on both sides of each scale line, eight scales are obtained, the scalesshown in the accompanying drawing being those of 3 inches, Ii -inch, l-inch, 3 -inch, gi-inch,%- ineh, 15-inch and i -inch.

Supposing that a draftsman desiresto mark on a sheet of-v-paper the-ends of. aline representing 5 feet on a scale of i-inch to the foot. Observing the scale of -inch-he draws the legs of the instrument apart until the. graduation ,Inanl;.,,,5,,is directly underneath the hair line on the crystal. Then the pin points of the instrument will beat the proper distance apart to prick on the paper the-ends of the, l-inecorrespondingto five feet on the sealeof%-inch to the foot. The other scales are usedlin precisely the same mannert With -the construction as heretofore described ,there would often be some inaccuracy i the operation; ofthe instrument due to the iostinotion between the teeth of the idler gear; wheel and those of either the pinion or the rack ln ordeitto'avoid this lost motion 1 provide a spiral spring -25; which sur rounds the hub of the pinion, of which one end is secured: to the pinionand the other is passedrthroughla hole'ina boss 30 extending inwardly ifn'om the inner surface of the easel 1. This spring-is at 'all times under tension and serves tomaintain the forward port-ion o-f a dniving t otlrofthe idler wheel -or raclrin contact with arear-portion of a driven toothroii' the pinlon or idler nvheel respectively rand also: operates in like manner iii-regard. to the tooth of the rack and idler Wheel-i It. is evident that day this means all cause; i are: eliminated. i

Through the othen arcuate slot 4: extends the stem-r291 of a handle 31, there heing securedto said-1 steniran arcuate guide piece 32 iiwhiehtoscilla'tes in saidslot-and serves as the. iothervend. ofone: is pivoted, as shown at 39 to ra boss -41 extending inwardly from theninnercsurtacelot-the. case, and the other end of': the, other ishpivotedyas shownlat 42, toian-extension43 of the leg :7 beyond the shait 12%011Wl1iCh-lifi.lSi pivoted; The boss 41 isiolinear with theshaft'lQ and the inner surta eeyof :the leg 2; and, consequently, by the. arrangement just-above described, the

--stem :29 iisdal-Ways 'maintainedmidway between the two legs-,that is tosay, inisuchi a siuoa that; if it "were extended, 'it: would pass through the shaft 12 in -a direction hiseoting;;rthe.angle betweenthe two 'legsn 1 It'isnof courseinecessary'that the "distance of theubosszal newt-he pivot 12 he tlievsame as the length of; the extension 43 heyondiits piuotgzand that the: two arms 38% are likewise equal; L The: -b0SSl14i1i: rigidly extending from ldstrmotion; andinaccuracy due to that the case 1 nvhich is rigid with the leg 2 may beiconsidered as a1 extension-ofsaid, leg.

To use theinstrument as a divider the legs are spread apart and used in the same manner as those. of anordinary divider.

To use the instrument as a proportional divider-the legs are spread apart until the points are at the ends of the line of Which it istdesired .to ascertain a given fraction or multiple, and note is made of the graduation markimmediatelybeneath the hair line 27 on some given scale, 'as for instance, the scale 1. Attentionis then directed-to. asoale Whichis indicated hy a number which is the same fraction or multiple of 1 as that to Which the lines'are to. beireducedrorwenlarged', and theulegs of "theilistrumentaiare 1 then movedinto sucha position thatthe number beforenoted. I appears innnediately "beneath the hair line of said latter scale;- The points of the instrument will" then be at the distance-required.k. For instance, suppose it 1 is required. liOlIllttIki'Oll a sheet of paper. a line onethir'd vof another. 'Tliewlegs are a spread apart; until] thadistance betweenthe points is' equal. to the length. of the dine, on

the original sheet and the graduatioinmark V of the {2-inch scale;thatiappearsimmediately beneath the hair line; isivnote "1:" The legs of the, instrument i are them moved 1untilxthe same igraduation nnark 011;:tl19 i scale ,ofi iinehiappeaars beneath the hair.- line The distanee between the pointsis then the-distance required.

A circular scale 44; graduated lIO-aSllQWfilQ- grees isalso formed our the. dial- 23,:- and to use they iustrument asna iprotnactor aeircle is described: with a Ai inchi radius, the legs are moved qapartwinitili the required; number of sdegrees on r the scale 4A1 -appears beneath the hair line, and thenv the points of theinstrurnent; are applied to the circumference of thecirele. Thennarks: then madeby the points willsuhtendiat; the center of the. circle the angle desired.

It is .to he understood "that theaimprovements herein described and-claimed may also .be applied to calipers or any other instruments for-Which they are appropriate.-

I claim: 1 An instrument of the character descr bed. comprising legs,;- a pivot therefor, a circular rack hauing internal gear teeth and movable withene of; saidlege, an idler gear wheel rotatahly i carried by, the other deg v and-meshing-with said raek,-.a rotary pinion meshing Withsaid gear- Wheel, am-indicating dial; rotatable about said pivot v and. adapted to rotate with .said 1 pinion: =andyhav'ing a graduated circular line on 1 said,- dial. concentric avith said pivot, and alsovhaving'a mark fixed-in relation to the other legin proximity to which; saidicircular linehmovesein its r0- 1 tatlon.

2. An instrument of the character described comprising legs, a pivot therefor, a circular rack having internal gear teeth and movable with one of said legs, an idler gear Wheel rotatably carried by the other leg and meshing with said rack, a rotary pinion meshing with said gear wheel, an indicating dial rotatable about said pivot and adapted to rotate with said pinion, and having a graduated circular line on said dial concen- 10 tric lWith said pivot, and also having a mark fixed in relation to the other leg in proximity to which said circular line moves in its rotation, and a spring for taking up lost motion between the toothed elements.

A. S. HAROOS.

Copies of this patent may be obtained for five cents each, by addressing the "Commissioner of latents, "Washington, I). 0." 

